1) Field of the Invention
The present invention relates generally to agricultural implements and, more specifically, to folding implements with vertically movable ground support wheels or other vertically movable elements.
2) Related Art
Folding implement frames are widely used for agricultural applications to provide a wide field-working width and a narrower transport width. Some implements have tool-carrying frames with five sections or more, including outermost wing sections that fold over corresponding inner wing sections for transport. The inner wing sections are hinged to a main frame section so that the folded inner wing/outer wing combination on each side of the implement can be folded to an upright transport position. In the transport position, tools and lift wheel assemblies on the opposite outermost wing sections are in close proximity to each other over the central portion of the main frame. The lift wheel assemblies or other vertically adjustable components on the outermost wing sections, if not fully retracted or moved to a particular storage position, can interfere with each other as the sections are moved towards their final transport positions. Such interference can result in component damage and limit the pivoting of the frame sections so that transport width is not minimized. In addition, the lift assemblies projecting outwardly from the inner wing sections in the transport position can increase the transport width and move the center of gravity of the sections outwardly.
Various devices have been employed to prevent interference, such as mechanical locks for wheel assemblies of the type shown in U.S. Pat. No. 4,974,684 assigned to Deere & Company. Relatively complex hydraulic control circuits such as shown in U.S. Pat. No. 4,700,784 have also been devised. However, these have not been entirely effective and are not readily adaptable to automatic control systems utilizing an implement control unit (ICU) which provides individual control of implement lift cylinders of the type shown in U.S. Pat. No. 5,957,218 also assigned to Deere & Company.